This application to the National Center for Research Resources is designed to improve the transgenic mouse facility at UCLA. Transgenic mice can be created in one of two ways: l. Microinjection of fertilized mouse eggs. 2. Microinjection of embryonal stem (ES) cells into blastocysts. As a result of either process, unique strains of mice are created that are of use to investigators at UCLA and elsewhere. Because of the specialized skills and equipment required to carry out these procedures, many institutions have set up fee-for-service facilities that will produce transgenic mice for interested scientists. The transgenic mouse facility at UCLA has been operating for nearly two years. There have been repeated infections in the colony, most notably with mouse hepatitis virus (MHV). Furthermore, the current location in which the mice are housed is not adequate for optimal breeding. In some cases, investigators have been provided with up to eight independently derived founder transgenic mice using a single construct. We would like to preserve these different founder mice, without having to breed and analyze all of them simultaneously. To correct these deficiencies the following are requested: l. Expenses for moving the Transgenic Mouse Facility to the new vivarium in the MacDonald Research Laboratory at UCLA. Funds for minor alterations to this space also are requested. Our goal is to have space for housing the 300-500 mice required for transgenic mouse generation and a nearby surgery/work room. The facility will then be housed in an area that is modern and well designed with regard to mouse breeding, security and maintenance of pathogen free animals. 2. Ventilated cage racks and laminar flow changing areas. These are requested in order to keep the mice in a specific pathogen free (SPF) state, even in a situation in which the technicians involved in cage changing and/or the scientists using the mice may have come into contact with mice that are not SPF. 3. A liquid nitrogen freezer. This is requested for the freezing and storage of embryos, so that all the useful strains generated can be maintained without continual breeding. In summary, these three items,will improve both efficiency of the transgenic mouse facility at UCLA and the health of the mice provided to the biomedical community.